The hazards of nitrogen oxides, mercury and other compounds present in flue gases have resulted in the imposition of strict standards limiting discharges of such chemical species. To meet these standards, it is necessary to remove a significant portion of nitrogen oxides, mercury and/or other chemical species present in exhaust gases from stationary or mobile combustion sources.
Denitrification or selective catalytic reduction (SCR) technology is commonly applied to combustion-derived flue gases for the removal of nitrogen oxides when passed through a catalytic reactor. SCR technology has progressed to where substantially all nitrogen oxides can be removed from a flue gas.
Effective and efficient removal of mercury from flue gases, however, has become increasingly difficult. Elemental mercury in flue gases does not adhere well to soot and/or other particulates making collection by conventional particulate collection methods, such as electrostatic precipitators, dust filters and scrubbers, difficult. Moreover, the environmentally demanding and destructive conditions associated with flue gas filtration and treatment render many mercury absorbing materials unsuitable for use in industrial processes such as pulse jet or reverse air applications.